Method and installation for producing foamed plastic parts

Abstract

The invention relates to a method for producing foamed plastic parts using carbon dioxide for foaming a plastic melt, wherein the carbon dioxide is introduced into the plastic melt in the region of a plasticizing unit (130).

Description

Technical area

[0001] The invention relates to a method for producing foamed plastic parts using carbon dioxide to foam a plastic melt. This method is characterized in that the carbon dioxide is obtained from the ambient air or atmosphere and thus contributes to reducing the carbon dioxide content in the atmosphere. Furthermore, the invention relates to a system that preferably operates according to a method designed according to the invention. State of the art

[0002] To limit the warming of the Earth's atmosphere, it is already known that the CO2 content, which has increased due to industrialization, can be actively reduced. So-called "Direct Air Capture" (DAC) systems can be used for this purpose (source: https: / / de.wikipedia.org / wiki / Direct_Air_Capture). Such a system is essentially characterized by the fact that, in a first facility, the carbon dioxide is absorbed from the ambient air by an adsorption material. In a second facility, the carbon dioxide is extracted from the carbon dioxide-enriched adsorption material in a desorption process, so that the carbon dioxide can then be permanently bound, e.g., by injecting it into geological cavities.

[0003] From DE 11 2018 005 746 B4 it is also known to use carbon dioxide from the exhaust air of industrial plants to produce, among other things, a nanocellulose extrusion foam.

[0004] Furthermore, it is known from EP 1 475 208 B1 and EP 2 260 997 B1 to introduce carbon dioxide into a plastic melt. This occurs during melt plasticization. Depending on the process, the gas is introduced either directly into the plasticizing cylinder or into the nozzle of the plasticizing cylinder. The carbon dioxide dissolves in the plastic melt under appropriate pressure and expands as soon as the plastic melt is injected into the mold. During volumetric filling, the gas expansion takes on the function of holding pressure, so that a plastic component is created without sink marks and with little warpage. The result is a plastic component with a compact outer skin and a so-called microcellular foam or foam with an integral density distribution (so-called integral foam). Disclosure of the invention

[0005] The inventive method for producing foamed plastic parts with the features of claim 1 has the advantage that the carbon dioxide extracted from the ambient air in a plant for reducing carbon dioxide is used to produce foamed plastic parts. This eliminates the need to subject the carbon dioxide to further treatment steps, for example, for its permanent storage. This results in, for example, energy savings and investment costs for such processes or plants. Rather, the plastic parts themselves serve to permanently bind the carbon dioxide required to produce the plastic parts.

[0006] Against the background of the above explanations, it is therefore provided in a method according to the invention for producing foamed plastic parts using carbon dioxide for foaming a plastic melt by introducing the carbon dioxide into the plastic melt in the region of a plasticizing unit with the features of claim 1 that the carbon dioxide is obtained from a device for reducing carbon dioxide from the ambient air using an adsorption material and is fed to the plasticizing unit.

[0007] The device for reducing carbon dioxide from the ambient air is in particular a CO2 separation device which is designed to separate carbon dioxide from the ambient air by means of a CO2 separation process (reversibly).

[0008] In the context of the present invention, the term "separation" encompasses any reasonable type of separation or capture of CO2 (carbon dioxide) from the air, whereby binding and / or adhesion and / or storage and / or absorption of CO2 molecules on a CO2 separation agent occurs.

[0009] In this case, the CO2 separation device can be designed, in particular, to separate the CO2 from a supplied air stream by means of a CO2 separation process, in which the separation occurs with the release of energy or heat to the air stream. The CO2 separation process is preferably a sorption process, in particular an adsorption process and / or an absorption process. Accordingly, the CO2 separation can be carried out, in particular, by means of at least one of the following processes or combinations thereof: chemical adsorption process physical adsorption process chemical absorption process physical absorption process

[0010] The CO2 separation device is further configured to release CO2 from the CO2 separation medium by means of a CO2 release process. Within the scope of the present invention, the term "release" encompasses any reasonable method of releasing or expelling CO2 (carbon dioxide) from the CO2 separation medium, whereby a dissolution and / or release and / or discharge of CO2 molecules from the CO2 separation medium occurs.

[0011] In this case, the CO2 separation device is particularly designed to release or dissolve the CO2 from the CO2 separation agent by means of a CO2 release process in which the CO2 is released from the CO2 separation agent by introducing energy or heat into the CO2 separation agent.

[0012] The CO2 separation process is preferably a desorption process. Accordingly, the CO2 can be released using at least one of the following processes or combinations thereof: chemical desorption process physical desorption process

[0013] Preferably, the CO2 separation device is designed to perform the CO2 separation process and the CO2 release process cyclically. In this case, the CO2 separation device is particularly designed to perform the sorption process and the desorption process cyclically. The basic functionality of the CO2 separation device can be implemented, for example, analogously to the aforementioned WO 2020 / 212146 A1.

[0014] Advantageous further developments of the method according to the invention for producing foamed plastic parts are listed in the subclaims.

[0015] In the event that the plasticising unit and the device for reducing carbon dioxide from the ambient air are located relatively close together, particularly in the area of ​​a shared (industrial) plant, it may be advantageous for the carbon dioxide to be supplied via a pipeline connecting the device for reducing carbon dioxide from the ambient air to the plasticising unit.

[0016] Alternatively, however, it can also be provided that the carbon dioxide extracted from the ambient air in the device for reducing carbon dioxide is stored in a mobile storage unit. Such mobile storage units are typically designed in the form of gas flanges used for storing gas, which can be stored as needed and fed to the plasticizing unit.

[0017] A particularly preferred development of the method provides that, in a recycling plant for foamed plastic parts, the carbon dioxide released during their shredding is used to produce new foamed plastic parts. In other words, this means that a closed carbon dioxide cycle is enabled, in which the carbon dioxide used in the production of the plastic parts can subsequently be recovered during recycling and used to produce new plastic parts.

[0018] In a further development of the last proposal, it can advantageously be provided that the carbon dioxide recovered in the recycling plant is fed directly to the plasticizing unit. Such direct feeding is possible, for example, if the plasticizing unit and the recycling plant are located close to each other, so that the carbon dioxide from the recycling plant can be fed to the plasticizing unit, for example, via a piping system. Alternatively, the plasticizing unit can also be supplied using gas cylinders.

[0019] In an alternative embodiment, however, it can also be provided that the carbon dioxide recovered in the recycling plant is fed to the device for reducing carbon dioxide from the atmosphere. Depending on the amount of carbon dioxide recovered by the recycling plant, additional carbon dioxide recovered from the ambient air can be added or supplemented. Such a process also has the advantage that the device for reducing carbon dioxide from the atmosphere can supply not only a plastic parts production plant with carbon dioxide, but also provide carbon dioxide as needed.

[0020] Furthermore, the invention relates to a plant for producing foamed plastic parts using carbon dioxide, wherein the plant preferably operates according to a method designed according to the invention as described so far. The plant comprises a device for reducing carbon dioxide from the ambient air using an adsorption material and a plasticizing unit for producing foamed plastic parts, wherein the plasticizing unit is at least indirectly designed to use the carbon dioxide obtained in the device for reducing carbon dioxide from the ambient air.

[0021] In a further development of such a plant, it can be provided that the plant additionally comprises a recycling plant for recycling foamed plastic parts, which is designed to feed carbon dioxide released during the comminution of the plastic parts at least indirectly to the plasticizing unit.

[0022] In particular, it can be provided that the recycling plant is designed to supply the carbon dioxide directly to the plasticizing unit and / or to the device for reducing carbon dioxide from the ambient air.

[0023] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings.

[0024] Short description of the drawing Fig. 1 shows a schematic representation of a plant for the production of plastic parts in connection with a recycling plant and a plant for the reduction of carbon dioxide from the ambient air. Embodiments of the invention

[0025] In the Fig. 1 A system 1000 is shown, which essentially consists of three components. The first component is in the form of a device 100 for producing foamed plastic parts (not shown in detail) using carbon dioxide. Furthermore, the system 1000 comprises a device 200 designed to extract carbon dioxide from the ambient air UL. This is done, for example, using a free-flowing or pourable adsorption material. Finally, the system 1000 comprises a recycling system 300 for recycling foamed plastic parts, wherein the plastic parts are characterized in that they comprise or contain carbon dioxide.

[0026] The system 1000 described so far enables a closed cycle of carbon dioxide, i.e., carbon dioxide obtained from the ambient air or the recycled plastic parts can be used to produce new plastic parts by means of the device 100.

[0027] The device 100 is designed in the form of an injection molding machine 110, which, for example, comprises a gas dosing unit 120, which serves to inject or introduce the carbon dioxide into a plastic melt. The injection molding machine 110 also has a plasticizing unit 130, for example in the form of an extruder, to produce the plastic melt, which is subsequently further processed into the plastic parts foamed by the carbon dioxide. Such an injection molding machine 110 is known from the prior art, and its operation will therefore not be explained in detail.

[0028] The device 200 for reducing carbon dioxide from the ambient air UL is coupled to a valve device 210 which serves to control the amount of ambient air UL introduced into the device 200.

[0029] The recycling system 300 comprises a pre-sorting device 310 with a conveyor belt 320 onto which the plastic material to be recycled is applied. A sensor 330 can be used to check the plastic material for the presence of carbon dioxide in the plastic parts. For this purpose, it can be provided, for example, that the plastic parts produced using carbon dioxide contain fluorescent additives or the like during production, which, for example, were added to the plastic melt in addition to the carbon dioxide by means of the injection molding machine 110. The sensor 330 can control a sorting unit, e.g., an air nozzle 340, to sort the plastic parts into different containers 342, 344.While, for example, plastic parts that do not contain carbon dioxide are sorted into container 342, plastic parts that are used in a subsequent recycling process to extract the carbon dioxide they contain and to use it to manufacture new or additional plastic parts are placed into container 344.

[0030] The plastic parts collected in container 344 by the pre-sorting device 310 are then first fed to a washing device 350 of the recycling device 300 to clean the plastic parts. The washing device 350 is characterized by a suction device 352 (not shown in detail), which can be used to collect any carbon dioxide released during the washing process. The washed and shredded plastic parts are then fed to a drying device 354, which dries the plastic parts using heat. A suction device 356 is also used here to collect or extract any carbon dioxide released.The plastic parts are then fed to a device 360 ​​with an extruder 362, which serves to melt the washed and dried plastic parts and process them into pellets so that the pellets thus obtained can subsequently be processed in the injection molding machine 110. The device 360 ​​also includes an extraction device 364 for collecting carbon dioxide.

[0031] The carbon dioxide obtained in the recycling plant 300 during the recycling of the plastic parts by means of the extraction devices 352, 356 and 364 is then fed to the device 200, for example by means of a piping system 370, wherein a measuring device 375 is integrated in the piping system 370, which detects the mass or volume flow of the carbon dioxide and feeds it as an input variable to a control device (not shown) of the device 200.

[0032] The carbon dioxide supplied to the device 200 via the piping system 370 is supplied by the device 200, possibly together with carbon dioxide obtained from the ambient air UL (controlled via the valve device 210), via a further piping system 380 to the injection molding machine 110. A control unit 390 of the injection molding machine 110 reports the current carbon dioxide requirement for producing the plastic parts via a control line 392 to the control device of the device 200, which provides the required amount of carbon dioxide by appropriately controlling the valve device 210.

[0033] The system 1000 described so far can be modified or altered in a variety of ways without deviating from the inventive concept. For example, it is conceivable to supply the carbon dioxide obtained during recycling not via pipelines or the pipeline system 370 to the device 200, but directly to the injection molding machine 110 or additionally to the injection molding machine 110. It is also not necessary to use a pipeline to transport the carbon dioxide; rather, the carbon dioxide can be stored in containers in the form of gas cylinders, as is known per se, in order to make it accessible to the device 200 or the injection molding machine 110. Similarly, it is also conceivable to supply the carbon dioxide obtained in the device 200 to the injection molding machine 110 not via the further pipeline system 380, but via containers or gas cylinders.

Claims

1. A method for producing foamed plastic parts using carbon dioxide for foaming a plastic melt, wherein the carbon dioxide is introduced into the plastic melt in the region of a plasticizing unit (130), characterized by that the carbon dioxide is obtained from the ambient air (UL) by means of a device (200) for reducing carbon dioxide using an adsorption material.

2. Method according to claim 1, characterized by that the carbon dioxide is supplied to the plasticizing unit (130) via at least one pipeline (380), wherein the at least one pipeline (380) connects the device (200) for reducing carbon dioxide from the ambient air (UL) to the plasticizing unit (130).

3. Method according to claim 1, characterized by thatthe carbon dioxide obtained in the device (200) for reducing carbon dioxide from the ambient air (UL) is stored in a mobile storage device, in particular a gas cylinder.

4. Method according to one of claims 1 to 3, characterized by that in the area of ​​a recycling plant (300) for foamed plastic parts containing carbon dioxide, during the recycling of which carbon dioxide released is used to produce new foamed plastic parts.

5. Method according to claim 4, characterized by that the recycling plant (300) has extraction devices (352, 356, 364) to extract carbon dioxide released during the production of the plastic parts.

6. Method according to claim 4 or 5, characterized by that the carbon dioxide obtained in the recycling plant (300) is fed directly to the plasticizing unit (130).

7. Method according to one of claims 4 to 6, characterized by thatthe carbon dioxide obtained in the recycling plant (300) is fed to the device (200) for reducing carbon dioxide from the ambient air.

8. Plant (1000) for producing foamed plastic parts using carbon dioxide, preferably according to a method according to one of claims 1 to 7, with a device (200) for reducing carbon dioxide from the ambient air (UL) using an adsorption material and a plasticizing unit (130) for producing foamed plastic parts by means of carbon dioxide, wherein the plasticizing unit (130) is at least indirectly designed to use the carbon dioxide obtained in the device (200) for reducing carbon dioxide from the ambient air (UL).

9. Plant according to claim 8, characterized by thatthe device (200) for reducing carbon dioxide from the ambient air (UL) is connected to the plasticizing unit (130) via at least one pipeline (380) in order to supply the carbon dioxide to it.

10. Plant according to claim 8 or 9, characterized by that the plant (1000) additionally comprises a recycling plant (300) for recycling foamed plastic parts containing carbon dioxide, which is designed to supply carbon dioxide released during the recycling of the plastic parts at least indirectly to the plasticizing unit (130).

11. Plant according to claim 10, characterized by that the recycling plant (300) is designed to supply the carbon dioxide directly to the plasticizing unit (130) and / or to the device (200) for reducing carbon dioxide from the ambient air.

12. Use of a plant according to one of claims 8 to 11 for producing plastic parts according to one of claims 1 to 7.

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